You can use any size and voltage of incandescent bulb.
The flash rate must be between 0.5Hz and 2Hz. The mark-space ratio is unimportant but the difference between the bulb being on and off must be clearly visible.
The flashing must be done electrically (i.e. causing the filament in the bulb to glow on and off). A bulb that is on continuously but has shutters, lenses etc. moving in front of it is not an eligible entry.
Your system doesn't have to have amazing longevity but it must be able to run for at least 5 minutes without breaking down, exploding etc.
How to enter:
Build your unusual system for flashing a light bulb and make a video of it in action (complete with the bulb flashing, the system that's making it flash and a detailed description of how it works). Upload your video to YouTube and include "Flashing Light Prize 2017" in the title. Then tweet us @FlashingSystems to let us know !
The contest is open until the 1st of August 2017 whereupon the judges will review all the YouTube clips and decide the winner.
Contest page: https://www.flashinglightprize.com/
Entries from other applicants: https://www.flashinglightprize.com/entries